Title description:
Implement the function to get the next permutation. The algorithm needs to rearrange the given sequence of numbers into the next larger permutation in lexicographical order.
If no next larger permutation exists, rearrange the numbers into the smallest permutation (i.e. ascending order).
Must be modified in-place, only extra constant space is allowed.
Example 1:
Input: nums = [1,2,3]
Output: [1,3,2]
Example 2:
Input: nums = [3,2,1]
Output: [1,2,3]
Example 3:
Input: nums = [1,1,5]
Output: [1,5,1]
Example 4:
input: nums = [1]
output: [1]
Problem-solving ideas:
class Solution:
def nextPermutation(self, nums: List[int]) -> None:
"""
Do not return anything, modify nums in-place instead.
"""
if len(nums) <= 1:
return
target1 = -1
for idx in range(len(nums) - 1, 0, -1):
if nums[idx] <= nums[idx - 1]:
continue
else:
target1 = idx - 1
break
if target1 == -1:
nums[target1 + 1:] = nums[target1 + 1:][::-1]
return
for idx in range(len(nums) - 1, target1, -1):
if nums[idx] > nums[target1]:
nums[idx], nums[target1] = nums[target1], nums[idx]
break
nums[target1 + 1:] = nums[target1 + 1:][::-1]
Algorithm performance:
